A recent study from South Africa contradicts the existence of an entourage effect — at least when it comes to the treatment of human cervical cancer cells.
There is a debate around medical cannabis concerning the benefits of using whole-plant vs. specific cannabinoid extracts. Modern medicine and regulatory institutions tend to favor the latter, as it provides more control and predictability when it comes to doses, therapeutic effects, and side effects. Some researchers and involved citizens, on the other hand, believe that whole-plant extracts could be more effective given the synergetic forces of the hundred compounds present in the plant.
The “entourage effect,” a term coined in 1998 by Ben-Shabat, refers to the multiplicative effects that otherwise inert substances can have when bundled together. In cannabis, this is better illustrated by terpenes, the molecules responsible for the plant’s unique smell. While these are not thought to have active pharmacological properties – illustrated by the FDA’s approval of their use in dietary products – they can alter the effects of cannabinoids by interacting with their receptors.
However, evidence from a recent study in South Africa contradicts the existence of an entourage effect, at least when it comes to the treatment of human cervical cancer cells. The authors demonstrated that Cannabidiol (CBD) alone, and at much lower concentrations than whole cannabis extracts, was capable of inhibiting cell growth and inducing cellular death in human cervical cancer tissue. The work of Dr. Sindiswa Lukhele and Lesetja Motadi extends previous findings showing the therapeutic effects of CBD on several human cell lines of breast and prostate cancer. The report is freely available in the journal BMC Complementary and Alternative Medicine.
To compare the efficacy of cannabis and CBD, the authors estimated the half maximal inhibitory concentration (IC50), which tells what concentration is needed to destroy half of the living cells. For different cell lines and cannabis preparations, the IC50 ranged between 50 and 100 μg/ml, whereas for CBD, the IC50 ranged from 1.5 to 3.2 μg/ml. This suggests that pure CBD extracts are between 15 and 65 times more potent than whole cannabis extracts.
Further analysis confirmed that cannabis and CBD share the same mechanisms when fighting cancer. Both compounds reduced energy levels in cells (ATP) to an extent that often leads to apoptosis (cell death), and they modulated the same proteins involved in apoptosis. When differences in the degree of change emerged, they were always in favor of CBD. In sum, the authors present compelling evidence that cannabis can curb cervical cancer in vitro, and that its effects are, for the most part, mediated by CBD.
Although these results refute an entourage effect in cancer fighting, they still suggest a potential window for a therapeutic effect of whole-plant cannabis extracts. In Canada alone, every year 1500 people are diagnosed with cervical cancer and 400 are killed by the disease, but these numbers pale in comparison to places with less readily available healthcare. The authors report estimates of half a million new cases and a quarter of a million deaths every year due to cervical cancer in Sub-Saharan countries. In some of these regions, where 80% of the population still relies on medicinal plants as the sole source of medicine, such a finding, if confirmed in human patients, would be of immeasurable value.
Featured image via Flickr.